I think I understand, you want the script to save files numbered ascending, so that when you have already saved file1.txt and file2.txt, the next one should naturally be file3.txt. To be honest I am not sure how to do that in Batch. In for example C# or AutoIt3 I would've used Regular Expressions to match the file names of all the text files, identified the highest number and then continued the numbering.

Here is an example of how you can loop just the files that are formatted as file[...].txt

Code:

@echo off
for %%i in (file*.txt) do echo %%i
pause

I'll get back to you if I come up with a solution, meanwhile maybe one of the Batch gurus will step in?